1. Technical Field
The present disclosure relates to a method for measuring a dimension of a target site. More particularly, the present disclosure relates to methods of projecting and correcting images for use in measuring a dimension of a target site.
2. Background of the Related Art
Minimally invasive surgery, e.g., laparoscopic, endoscopic, and thoroscopic surgery, has many advantages over traditional open surgeries. In particular, minimally invasive surgery eliminates the need for a large incision, thereby reducing discomfort, recovery time, and many of the deleterious side effects associated with traditional open surgery.
The minimally invasive surgeries are performed through small openings in a patient's skin. These openings may be incisions in the skin or may be naturally occurring body orifices (e.g., mouth, anus, or vagina). In general, insufflation gas is used to enlarge the area surrounding the target surgical site to create a larger, more accessible work area.
During minimally invasive procedures, it is often difficult for a surgeon to determine sizes of various organs, tissues, and other structures in a surgical site. Various in-situ surgical metrology methods exist for measurement in a surgical site. Such methods require many moving parts and projection images that change size and/or focus quickly as projectors move in or out of a surface of projection.
In-situ surgical metrology optical projection methods are employed in situations where it is desired to measure the size of defects and to correlate the size of the defects with commercially available mesh sizes for ventral hernia repair. Such methods often employ an optical projection device that includes a laser light source and diffractive optics to generate a light pattern on an area of interest. In other methods, a light source and lens system is used to project an image on the surgical site.
In projected-pattern metrology, the projected image or pattern serves as an optical ruler, where the distance between dots or lines in the pattern is directly translated to actual distances. In laparoscopic applications, when the instrument is inserted through a laparoscopic port, it is not always possible to position the projection device in front of the site to be measured. When the surface of the projection is tilted or offset with respect to the optical axis, the projected image becomes distorted, which results in significant reduction in accuracy of the measurements. Numerical methods to correct for the reduction in accuracy are not always available for the particular scenarios encountered.